Reasons range from simply not getting enough sleep to illnesses such as anemia, reports The Week UK.

If you’re suffering sleep problems, it may be down to your microbial make-up. “The friendly bacteria within our gut, known as our gut microflora, are vitally important to our well-being, including our sleep. In fact, they produce hormones and chemical neurotransmitters that help calm and relax us,” says Bustle.